Conventional lock cylinders include a first mechanical locking mechanism operated by mechanical means, which first mechanical locking mechanism cooperates with a second mechanical locking mechanism operated by electromagnetic means. Conventionally, the mechanical means for in situ opening of a closure can include a door knob, door latch, keys, etc., while the electromagnetic means actuates the same closure from a remote position.
For example, the independent position of the operating or actuating point for manipulating the electromagnetic means permits a central monitoring of, in part, remotely positioned closures. This monitoring can take place in a time-dependent and fully automatic manner, by the action of an operator, by applying preset states, etc.
In general, the electromagnetic means constitutes a additional closing means, relative to the mechanical means, and is used in a conjunctive or disjunctive manner. These AND and OR possibilities extend the uses of closures, particularly in the organizational manner. This is shown by the following truth table in the case of a door:
______________________________________ Mechanical Electromagnetic ______________________________________ 0 0 Door open to anybody 1 0 Only key holders have access. 0 1 Access given by control room. 1 1 Control room gives access to certain key holders. ______________________________________
The two alternative key or control room possibilities extend the organizational possibilities. The conjunctive key and control room possibility increases security.
The advantages of such combined closures are described and used in DE-OS No. 2,325,566. The mechanical means for operating the closure, which is a door closure, are knobs arranged on the door for sliding a bolt. The electromagnetic means operate an additional bolt, which locks or releases the main bolt as a function of the additional bolt position. In addition, a safety cylinder is provided for operating or releasing the electromagnetically operated additional bolt, with the safety cylinder being associated with an interrogation of polling means. The electromagnetic part and the safety cylinder releasing the electromagnetic means are housed in the door frame. The safety cylinder exclusively operates the electromagnetic locking mechanism with the aid of a specially machined notch bit key, which key has the information for the reading device in the key back. The electromagnetic release can also occur disjunctively, i.e., in a key or control room form.
The Journal "Baubeschlag Magazin", No. 10/80 (October 1980) describes another combined closure. An additional bolt operated by electromagnetic means locks the main bolt. The additional mechanical locking mechanism, which is manipulated by means of a safety cylinder using a key, is housed together with the electromagnetic means in the door lock box, not separately in the door and frame. The lock bolt is locked in the rear bolt part and not in the front bolt part.
The locking of a bolt acting between the door and the frame, either by a device in the frame or a device in the door, requires a special design for the closure. For example, subsequently providing an electromagnetic additional locking mechanism in existing closures of any random type, particularly doors, requires modifications to the mechanical part of the lock. Preferably, an existing lock is replaced by one intended for electromagnetic additional locking, or already manufactured therewith.
This replacement involves high costs because otherwise complete locking mechanisms are replaced, often involving additional modifications to existing doors or door frames. The possible additional security is consequently often not used due to the expense, particularly if a relatively large number of closures have to be modified.